We don't have a specific feature that prevent the parent's location from showing up on the map. the reason is because we want to build trust through transparency and the intent of the feature is to allow for the family to see each other on map. With that said, if your wife is on an iPhone, you/she can disable permission to the location (settings -> privacy -> location services -> Safe Family -> change to "never" and that will prevent your wife's device from sharing location. unfortuntely there isn't an equivalent control on the android side to disable just location for just safe family.
hope that helps,